I am building a dry cell HHO system from purchased plans. This system call for 5 plates but only the two outer plates are connected to power. I was told that I could add two additional plates for added output. I have been all over the web looking and reading about HHO and building plans. I am only getting confused not enlightened. Everyone has an opinion and these conflict more often than not. I can understand one energized positive plate reacting to a energized negative plate but these neutral (non energized plates) I do not understand. Right now my plans are two outer energized plates and five plates sandwiched between them with no power connections. Is this a sound design? All my plates are separated with 3/32" thick EPDM gaskets. Thank You

Here's some of the missing theory: HHO is best produced when the voltage between the plates is about 2.1 or 2.2 volts or so. 12 volts generates too much heat and makes a bunch of steam, below 2.0 volts is not enough to break up the water molecule reliably. So 2.2 volts is more or less the target voltage that makes HHO most efficiently.

With 5 neutral plates between your 12 volt hot plates (actually 13.5 volts when the engine is running) will give you a plate to plate voltage of about 2.2 volts. That's why you've been steered to that design.

Get some electrolyte in there and start making some gas. Then take your meter and measure the voltage between the plates. They will vary a bit, but will be around 2.1 to 2.2 volts. That will give you a good practical understanding of why you have the neutral plates.